Monobloc dead spot

Hi Triton Trasher.

Not my case. The beggining of this story is the Domi running with a K68, a russian carb working properly and making a good 25Km/L average consumption. The bike was not fastest, but it was OK

I have a monobloc that I have tried years before exactly with this dead spot problem.

Recently I decided to give it a second try. The monobloc was the best idler and the better performer, not match....but I was VERY rich from idle to 1/4

So I change the needle jet and made the cutaway higher (from 3 to 4). This was good! Idling was still very good and every stage was on tune, 1/8, 1/4, 1/2, Full.....but

There is a small dead stop just after idling.

If I made the idle richer the problem gets worst. If I made the idle leaner the idle is not perfect, but the problem gets better. That's why I am not pretty sure that a bigger idle jet could cure this.

I haven't tried a bigger idle jet because I haven't found proper drills.
 
Yasser Fernandez said:
Hi everyone.

I own a Norton Dominator 99. Using a monobloc carb that starts and runs very smooth except in a point.

¨ The bike would still run well but when you slowly opened the throttle the engine would slow down before it speeded up. You had to open the throttle quickly to get by the dead spot. I was used to that it wasn't bad. ¨ I used the exact words I found on another thread because the are ideal as a fault description.

Ideas?
Click to expand...
If it hasnt got the chock fitted then make sure the cable hole is blocked.Put gasckets on ALL faces,even over the rubber O ring . Sounds like a vacume leak.
 
Inbetween the transition from pilot to needle jet the bypass drilling supplies fuel (from the pilot jet) and air. A small increase in the pilot jet size may help but wear to the slide and body is probably the problem. If a coating of grease on the slide reduces the unwanted air leak and weak spot this may help pinpoint the problem.
 
A no 4 slide is too big ,a 99 would usually need a 3 or 31/2 , the 4 slide is probably there trying to compensate richness from a worn needle jet, If the slide can move forward and back when fully down then wear to the slide/body will give you hiccups just off tickover.
 
Yea 3 1/2's with the needles a notch past 1/2 up . for starters .

Though you can file bigger slide cuttaways , its a bit hard to file them smaller .

If you have a think you can figure the point at which these things work , so going through it , on the road
you can watch / listen for 'Its correct 'or not . WHEN ITS WARM .

Mint Cond. monoblocks carburate nice'n accurate . You start at the TOP , ( Mains )
get a vauge check 'off the line '( cuttaways ) But - Fine Tune the needle hight .

You want zero wear needles etc etc if you can . Later , there differant tapers if they insist on being awkward .

Aces of old would hand finish them to suit - fine tune . Or theyed have a selection of jets & needles .

AND CHECK THE FLOAT HIGHT , carefully . before you do anything else . Bias rich rathern lean . If you must .
Worn Tramlined slides and its hit & miss . gotta be good if its gunna be set dead right . Or it'll sound like concentrics . :(
 
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